Excimer laser coronary angioplasty: a mini-narrative review of clinical outcomes

Background Excimer laser coronary angioplasty (ELCA) has evolved as a pivotal element in percutaneous coronary intervention (PCI), significantly influencing procedural efficacy and safety. This mini-narrative review explores ELCA's applications, focusing on its efficacy and clinical outcomes. Body A search of major databases identified studies from ELCA's inception. Inclusion criteria encompassed diverse study designs exploring ELCA in coronary interventions, with rigorous data extraction ensuring accuracy and completeness. A narrative synthesis presented key findings across studies. ELCA demonstrated promising outcomes compared to traditional PCI and stent placement. Reduced reperfusion time, enhanced microcirculation, and lower postoperative major adverse cardiac events (MACE) rates highlighted its efficacy. Improved vascular and lumen dynamics, plaque modification, and successful treatment of complex lesions showcased its versatility. Quality of life enhancements positively impacted long-term recovery, particularly in acute coronary syndrome (ACS) cases. ELCA's success in challenging scenarios and its role in refining in-stent restenosis (ISR) treatment indicated broader applications. Despite limitations in some studies, ELCA presented a favorable safety profile. Conclusion The review underscores ELCA's dynamic role in coronary interventions, offering a promising tool for enhancing procedural outcomes. Clinical implications include improved reperfusion, adaptability in complex lesions, and potential long-term benefits for ACS patients. While integration into routine practice requires careful consideration, ELCA's positive outcomes encourage further exploration and innovation in interventional cardiology.


Background
Coronary artery disease (CAD) remains a global health crisis [1].Percutaneous coronary intervention (PCI), also known as angioplasty, has emerged as a cornerstone treatment for this condition [2].This minimally invasive procedure involves navigating a catheter with a tiny balloon to the blocked artery and inflating it to restore blood flow.Despite its effectiveness, conventional balloon angioplasty with stenting faces limitations.Certain complex lesions, such as heavily calcified plaques, in-stent restenosis (re-narrowing within a previously placed stent), and chronic total occlusions (complete blockage), can pose challenges for balloon dilatation alone [2].In these scenarios, excimer laser coronary angioplasty (ELCA) offers a valuable tool within the PCI armamentarium.
ELCA has become an integral component of percutaneous coronary intervention PCI, significantly influencing both the efficacy and safety of the procedure [1].As a complementary method, ELCA is employed alongside conventional PCI, crucial in enhancing outcomes in suitable cases [1,2].Originating to improve revascularisation results for patients with coronary artery disease, ELCA seamlessly integrates into the nonsurgical angioplasty process [3].This innovative technique involves using an inflatable balloon-tipped catheter to address coronary artery constriction or blockage resulting from underlying atherosclerosis [3,4].
In response to the limitations posed by earlier laser technologies, ELCA has evolved into a dynamic tool within nonsurgical angioplasty procedures [5,6].Its application has demonstrated particular promise in treating challenging lesions resistant to conventional methods [7,8].Lasers, including excimer lasers, consist of an excitation source (pump) and an optical resonator with mirrors [9].The active medium (solid, liquid, or gas) determines the laser's emitted wavelength, with the excitation source energizing atoms in the active medium [10].Laser function is governed by stimulated emission of radiation, producing intense, monochromatic, and coherent light [11,12].
In interventional cardiology, lasers operate in pulses, delivering high-intensity light through fiber optics [13].Excimer lasers, utilizing xenon gas and hydrogen chloride, emit UV light (308 nm) with minimal tissue absorption, thus reducing collateral damage [14].The wavelength determines penetration depth, with UV lasers exhibiting less depth and heat, making them advantageous for clinical applications [15].Over the past 25 years, ELCA has played a pivotal role in percutaneous interventions for coronary artery stenoses, garnering renewed interest in treating various complex lesion subsets [16].Utilizing a pulsed ultraviolet laser catheter, ELCA has proven effective with minimal thermal damage, as demonstrated in its initial application for atherosclerotic tissue vaporization in 1985 [17].Recent reports highlight its resurgence in addressing complex coronary diseases, including in-stent restenosis (ISR), debulking Saphenous Vein Graft lesions, interventions for Chronic Total Occlusion, and treatment of thrombotic lesions [18][19][20].
With ongoing procedural refinements, advancements in laser technology, and expanding clinical applications, ELCA stands as a dynamic and promising tool in the evolving landscape of interventional cardiology.Its renewed success in managing complex coronary diseases suggests exciting prospects for further innovation and contributions to improved patient outcomes.This review aims to comprehensively evaluate the applications of ELCA, with a specific focus on assessing its efficacy, safety profile, and clinical outcomes.

Literature search strategy
We initiated our review by systematically searching major electronic databases, including PubMed, MED-LINE, Embase, and the Cochrane Library.Employing a comprehensive set of keywords such as "Excimer Laser," "Coronary Angioplasty," "ELCA Efficacy," "ELCA Safety," and "Clinical Outcomes of ELCA," we aimed to capture a diverse array of studies dating from the inception of ELCA technology to the December, 2023.

Inclusion and exclusion criteria
Our criteria for inclusion involved studies that looked into ELCA in coronary interventions, encompassing diverse research designs, such as randomized controlled trials (RCTs), observational studies, case series, and reviews.Exclusions were made for studies lacking primary outcome measures pertinent to ELCA efficacy, safety, or clinical outcomes, reviews, conference abstracts, as well as those offering insufficient data or presenting inadequate reporting and studies published more than a decade ago.

Data extraction
Systematic and thorough data extraction was performed from the selected studies.This involved gathering details on study design, sample size, patient demographics, procedural intricacies, and primary outcomes encompassing efficacy, safety, and clinical outcomes.Rigorous crossverification ensured the extracted data's accuracy, consistency, and completeness.

Data synthesis and analysis
A narrative synthesis was undertaken to group key findings, presenting a cohesive summary of outcomes and trends across studies.

Current evidence for ELCA
The ELCA has demonstrated promising results compared to alternative treatment modalities, including traditional coronary angioplasty and stent placement.Multiple studies have reported positive outcomes, offering valuable insights into the potential advantages of this therapeutic approach (see Table 1).

Reduced reperfusion time
In the 2023 Ambrosini et al. 2015 study, ELCA demonstrated a shorter door-to-balloon time than Thrombus Aspiration (TA) [21].The ELCA group exhibited an enhanced Myocardial Blush Grade (MBG)  [27].ELCA demonstrated efficiency in plaque removal and thrombus vaporization, potentially stabilizing thrombus within culprit lesions.It appeared effective in reducing myocardial enzyme elevations, indicative of reduced plaque burden and a smaller infarction size.Notably, Sasaki et al., 2022 reported high success rates in achieving lumen expansion, particularly in ST-segment elevation myocardial infarction (STEMI) cases [23].Shibata et al. 2022 suggested that ELCA usage resulted in shorter stent lengths and reduced balloon usage, indicating improved plaque and thrombus removal, potentially leading to direct stenting and less myocardial damage [23].Similarly, Harima et al., 2018 reported the excimer laser's success in treating various lesion types, including diffuse lesions, chronic total occlusions, and in-stent restenosis [24].In Hirose et al. 's 2016 study, ELCA effectively reduced neointimal plaque area, though the exact mechanism behind this advantage remained unclear [26].

Quality of life improvements
The shortened reperfusion times achieved with ELCA contribute significantly to better outcomes and improved quality of life for patients experiencing Acute Coronary Syndrome (ACS) [23,24].The ELCA group exhibited promising outcomes, including quicker reperfusion and improved blood flow.It reduced adverse events compared to Thrombus Aspiration (TA), suggesting its potential as a favorable intervention for ACS.In the study by Shimojo et al. (2023), improvements in Left Ventricular (LV) function and the potential reduction in infarction size with ELCA were highlighted, contributing to a better quality of life for patients recovering from ST-segment elevation myocardial infarction (STEMI) [22].Additionally, findings from the study conducted by Sasaki et al. (2022) suggest that ELCA can modify plaque composition, leading to improved blood flow and potentially better patient outcomes [25].
The study by Shibata et al. (2022) indicated that ELCA offers advantages in myocardial salvage, potentially reducing infarction size and preserving cardiac function, thereby positively impacting patients' long-term quality of life.[23] ELCA showed promise in improving myocardial salvage in STEMI patients undergoing percutaneous coronary intervention (PCI), suggesting its potential as a beneficial strategy for this specific patient population.Moreover, the study by Hirose et al. (2016) suggests that using ELCA as a pre-treatment strategy before scoring balloon dilatation is associated with better outcomes in In-Stent Restenosis (ISR) treatment [26].This is primarily attributed to ELCA's impact on reducing neointimal plaque, facilitating better long-term results, and maintaining improved blood flow, collectively enhancing the quality of life for patients undergoing this particular intervention.

Study limitations
The study conducted by Arai et al. [27] faced limitations due to its retrospective, single-center design with a relatively small sample size and a mixed population, including non-ST segment elevation myocardial infarction and unstable angina pectoris, exceeding recommended reperfusion times.The peak creatine kinase (CK) levels did not show significant differences between the ELCA and Thrombus Aspiration (TA) groups.Despite the benefits of ELCA, there was no demonstrated advantage in other parameters reflecting myocardial viability or Left Ventricular (LV) diastolic function.No significant difference in myocardial salvage was observed between the ELCA and aspiration groups, and there was no significant improvement in LV diastolic function in either group.
Harima et al. [24] revealed that unplanned stenting was more common than expected in patients initially scheduled for Drug-coated Balloon (DCB) with ELCA.The combined strategy of DCB and ELCA did not yield a more gratifying outcome compared to traditional stentbased interventions.Shibata et al. 2022 also reported a limited effect on Final Thrombolysis in Myocardial Infarction-3 (TIMI-3) flow and slow-flow prevention with ELCA [23].ELCA did not demonstrate a significant advantage in achieving final TIMI-3 flow or preventing slow-flow phenomena compared to conventional Percutaneous Coronary Intervention (PCI), possibly due to the reduced use of aspiration therapy and distal protection devices in the ELCA group.
In terms of morbidity and mortality, the Shibata et al. 2022 study suggested that ELCA could be beneficial for myocardial salvage in early ST-segment elevation myocardial infarction (STEMI) cases but did not show clear advantages in achieving final TIMI-3 flow or preventing slow-flow complications compared to conventional PCI [23].Harima et al., 2018 reported that about one-third of patients initially intended for DCB with ELCA underwent unplanned stenting, potentially affecting procedural safety [24].The study reported similar frequencies of major adverse cardiac events (MACEs) across treatment groups but varied rates of target vessel revascularisation (TVR).No myocardial infarctions were reported during the follow-up period, and the overall mortality rate was not mentioned.Bleeding events requiring transfusion or surgical repair occurred in a small percentage (3.3%) of patients in the DCB with ELCA group during follow-up.Similarly, according to Hirose et al. [26], no procedureassociated adverse events such as myocardial infarction, emergency bypass surgery, or in-hospital deaths were recorded during the study.

Future directions and recommendation
The examination of ELCA in this review established its effectiveness compared to alternative methods like traditional coronary angioplasty and stent placement.
The demonstrated reduction in door-to-balloon time and improved microcirculation associated with ELCA, as evidenced by elevated MBG and reduced MACE rates, suggests a tangible benefit for patients experiencing acute coronary events.The swift reperfusion achieved through ELCA has direct implications for minimizing myocardial damage and improving overall patient outcomes.The positive impact of ELCA on vascular and lumen dynamics, including increased vessel and lumen volume and favorable shifts in plaque composition, opens avenues for more refined and patient-specific interventions.This enhancement in procedural adaptability, particularly in optimizing stent placement and addressing diverse lesion complexities, has practical implications for tailoring interventions to individual patient needs.
The shortened reperfusion times achieved with ELCA contribute to immediate clinical benefits and potential improvements in long-term quality of life for patients recovering from ACS.The reduction in infarction size, modifications in plaque composition, and improvements in LV function collectively suggest a positive impact on patients' overall well-being and functional recovery postintervention.The findings indicating ELCA's efficacy in reducing late luminal loss, recurrent restenosis, and improving blood flow have implications for reducing procedural complications.This may result in fewer adverse events, including target vessel revascularisation (TVR) and major adverse cardiac events (MACE), contributing to improved procedural safety and long-term stability.
ELCA's success in treating challenging lesions such as diffuse lesions, chronic total occlusions, and in-stent restenosis suggests its utility in scenarios where traditional interventions may face limitations.This expands the armamentarium of interventional cardiologists, offering a potential solution for cases historically associated with increased procedural complexity.ELCA's positive outcomes in treating ISR, as indicated by reduced neointimal plaque area and relatively lower recurrent restenosis rates, suggest a role in refining ISR treatment strategies.The potential to stabilize thrombus within culprit lesions and minimize myocardial enzyme elevations contributes to the safety and feasibility of ELCA in this specific context.
ELCA's positive impact on myocardial salvage, particularly in early ST-segment elevation myocardial infarction (STEMI) cases, positions it as a consideration in the acute phase of ACS.The potential benefits of preserving cardiac function and reducing infarction size may influence decision-making in the emergent setting.The overall positive outcomes presented in this review prompt consideration for integrating ELCA into routine clinical practice.However, the learning curve associated with ELCA and the need for careful patient selection should be acknowledged.Institutions may need to evaluate the feasibility of incorporating ELCA into their standard protocols, considering its potential benefits and challenges.

Limitations and strengths
The review presents robust arguments that enhance its reliability and contribute to a better understanding of ELCA.Nevertheless, certain limitations need to be acknowledged.The review exclusively focuses on studies between 2015 and 2023, potentially excluding significant research conducted before or after this timeframe.Additionally, by restricting the scope to papers written in English, there is a possibility of overlooking valuable studies published in other languages, thereby introducing a language bias.

Conclusions
This review reveals ELCA's transformative potential in PCI.The evidence across various studies positions ELCA as a promising therapeutic intervention, showcasing its efficacy and safety compared to traditional approaches like coronary angioplasty and stent placement.These outcomes have direct implications for minimizing myocardial damage during acute coronary events, thereby presenting a tangible clinical benefit.ELCA's positive impact on vascular and lumen dynamics, including enhanced vessel and lumen volume, underscores its versatility in addressing diverse lesion complexities, providing clinicians with a nuanced approach to tailored interventions.
Moreover, ELCA exhibits a promising role in improving the quality of life for patients recovering from ACS.The observed reduction in infarction size, plaque composition modifications, and LV function enhancements collectively contribute to a favorable longterm prognosis.ELCA's success in treating challenging scenarios, such as ISR and complex lesions, expands the repertoire of interventional cardiology, offering a potential solution where traditional methods might face limitations.Despite these promising outcomes, the review acknowledges the limitations in some studies, emphasizing the need for careful consideration and patient selection.The learning curve associated with ELCA and the potential challenges necessitate a balanced evaluation for its seamless integration into routine clinical practice.